The publication of a study that showed that the internal nucleus of the earth has begun to turn slower than the mantle had a great media impact two years ago. Now, a team of researchers has used even more precise measurements of seismic waves and provides a new finding: the nucleus not only its speed has variedbut it is also changing shape.
In this new work, published Monday in the magazine Nature Geosciencethe team of John Vidale It has analyzed the seismic waves generated by 168 pairs of repeated earthquakes before and after 2010, the date on which the slowdown was identified, which means that any difference in seismic waves within each pair could not be due to differences caused by speed of rotation
The authors discovered that the waves that only touched the internal nucleus are different, which, as they maintain, would be explained by temporary changes in the form of the internal nucleus. According to Vidale and his team, the changes seem to be located near the surface of the internal nucleus, which can suffer a viscous deformation, changing its shape and moving in the superficial limit. “What we end up discovering is evidence that the surface close to the internal nucleus of the Earth undergoes structural changes,” says Vidale.
What we end up discovering is evidence that the surface close to the internal nucleus of the Earth undergoes structural changes
John Vidale
– Researcher at the USC and main author of the study
The authors also believe that the finding sheds light on the small alterations that the duration of the day is experiencing, which could be connected to the current deceleration of the internal nucleus. “It is known that the molten external nucleus is turbulent, but it had not been observed that its turbulence disturbed its neighbor, the internal nucleus, in a human time scale,” says Vidale. “What we are observing in this study for the first time is probably that the external nucleus disturbs the internal nucleus.”
A new unknown effect
“This new study comes to solve the controversy about these changes that had been measured in the speed of seismic waves,” he explains Nahúm Méndez Chazarrageologist and disseminator. “And it brings a very interesting conclusion that confirms that, indeed, the speed of rotation of the nucleus is changing over time, but another effect could be added: changes in the relief of the internal nucleus itself.”
In Chazarra’s opinion, this gives us a very different image of the internal nucleus, which is no longer a “static” layer, without changes, and that is rotating in unison. “What we see is precisely the other way around, a dynamic place where there are changes that we will now be able to recognize better thanks to seismic waves.”
What we see is that the nucleus is a dynamic place where changes are produced that we will now be able to recognize better thanks to seismic waves
Nahúm Méndez Chazarra
– Geologist and disseminator
“There is no doubt that the center of the Earth is one of the most mysterious and inaccessible places on the planet,” he says Maurizio MattesiniProfessor of Geophysics at the Complutense University of Madrid (UCM), in statements to the SMC. With a temperature of between 6,000 and 7,000º, remember, “the solid internal nucleus of the Earth plays an important role in the maintenance of the magnetic field of the planet and power the tectonics of plates, both fundamental elements for life on earth and in other land planets ”.
The intensity of the magnetic field is due to the movement of iron in the external nucleus and both nuclei are coupled by electromagnetic forces, remember Javier Fernández LozanoGeophysicist of the University of León. For this reason, a variation in one should condition the behavior of the other, “but knowing to what extent is more complicated and it is convenient to be cautious until there are more jobs about these interactions and their possible effect on the Earth’s magnetic field.”
“Knowing how the terrestrial interior works is essential to understand the processes that occur on the surface,” adds Fernández Lozano. “Volcanism, seismicity, plate movements, are processes that show the interaction between the different layers of the planet, from the outermost to the deepest. Knowing better the second, will also improve knowledge about the former. ”
For Mattesini, the result is very interesting because “it shows that there may be simultaneous changes in its rotation and form, the latter being an aspect that deserves a much more detailed investigation,” he says. “A deeper analysis of anomalies in the form of the internal nucleus could lead to rewriting the multidecadal history of its differential rotation with respect to the rest of the earth.”
#nucleus #Earth #reduced #speed #surface #changing #shape
